This invention relates to pressure responsive valve assemblies adapted for use in reciprocating piston-type compressors, such as refrigeration compressors, and more particularly to an improved port design and sealing arrangement for such valve assemblies.
Reciprocating piston-type compressors include suction and discharge pressure actuated valving mounted at the end of the cylinder between the cylinder head and the cylinder housing. In designing these valve assemblies it is important to overall system operation to provide a sufficiently large port area to permit passing the maximum volume of gas within a given time period and at an acceptably small pressure drop. This is particularly true for refrigeration compressors because of relatively high mass flow rates.
Associated with the desirability to maximize port area for a given size cylinder is the need to reduce the stress in the moving reed member without adversely affecting its ability to close the port. In prior apparatus these ports have been configured to be generally circular and/or slightly rectangular or racetrack in shape. In situations wherein the refrigeration gas has not been fully vaporized, the compressor tries to pump liquid, resulting is what is termed "slugging". In this situation, the extremely high cylinder pressures generated (e.g., 1,000 psi or more) can cause the suction valve reed to bend or deform thereby not completely closing the port and in extreme cases the slugging could cause the valve reed to be pushed through the suction port.
A gasket disposed between the compressor body and the valve plate is typically used to inhibit leakage between the compression cylinders. Hermetic-type compressors are tightly sealed such that if the gasket should fail due the high pressure differential between the ports, the compressor cannot be easily serviced. Accordingly, an enhanced gasket retention arrangement is desirable.
It is an object of this invention to provide a motor compressor assembly wherein the stress in the reed valve is reduced. In this regard, there is provided a unique port design which enhances the resistance of a reed to failure from fatigue or slugging. A benefit of such an arrangement is that for the same reed shape a reduction in the thickness (and thus the mass) of the reed can be utilized to reduce impact stresses and noise and increase response.
It is a further object of this invention to provide an arrangement which ensures that the seal between the compression cylinders is maintained. In this regard there is provided a unique gasket mounting arrangement which provides a mechanical interlock with the gasket when sandwiched between the compressor body and valve plate. A benefit of such an arrangement is the prevention of gasket blow-out which can be caused by the extreme pressure differentials as the pistons reciprocate in their respective adjacent cylinders.